マルチキャスト送信とマルチキャスト受信のソースコード例

    #include <stdlib.h>  
    #include <sys/types.h>  
    #include <sys/socket.h>  
    #include <netinet/in.h>  
    #include <arpa/inet.h>  
    #include <time.h>  
    #include <string.h>  
    #include <stdio.h>  
    #include <unistd.h>  
      
    //#define HELLO_PORT  12345  
    //#define HELLO_GROUP "225.0.0.37"  
    #define MSGBUFSIZE 32*1024  
      
    int main(int argc, char *argv[])  
    {  
		if (argc != 4)
		{
			printf ("%s  mulitAddr  port  bindIP
");
			exit(129);
		}
		char* multiAddr = argv[1];
		int port = atoi(argv[2]);
		char* bindIP = argv[3];
		
		printf ("%s:%d
", multiAddr, port);
		printf ("bindIP = %s
", bindIP);
		
        struct sockaddr_in addr;  
        int fd, nbytes,addrlen;  
        struct ip_mreq mreq;  
        char msgbuf[MSGBUFSIZE];  
      
        u_int yes=1; /*** MODIFICATION TO ORIGINAL */  
      
        /* create what looks like an ordinary UDP socket */  
        if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0)   
        {  
            perror("socket");  
            exit(1);  
        }  
      
      
        /**** MODIFICATION TO ORIGINAL */  
        /* allow multiple sockets to use the same PORT number */  
        if (setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) < 0)   
        {  
            perror("Reusing ADDR failed");  
            exit(1);  
        }  
        /*** END OF MODIFICATION TO ORIGINAL */  
      
		unsigned long nip = inet_addr (bindIP);
        /* set up destination address */  
        memset(&addr,0,sizeof(addr));  
        addr.sin_family=AF_INET;  
        addr.sin_addr.s_addr=INADDR_ANY; /* N.B.: differs from sender */  
        addr.sin_port=htons(port);  
      
        /* bind to receive address */  
        if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0)  
        {  
            perror("bind");  
            exit(1);  
        }  
      
        /* use setsockopt() to request that the kernel join a multicast group */  
        mreq.imr_multiaddr.s_addr=inet_addr(multiAddr);  
        mreq.imr_interface.s_addr=inet_addr(bindIP);//htonl(INADDR_ANY);  
        if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0)   
        {  
            perror("setsockopt");  
            exit(1);  
        }  
      
	    FILE* fp = fopen ("./xxxx.ts", "w+");
        /* now just enter a read-print loop */  
        while (1)   
        {  
            addrlen=sizeof(addr);  
            if ((nbytes=recvfrom(fd, msgbuf, MSGBUFSIZE, 0, (struct sockaddr *) &addr,(socklen_t*)&addrlen)) < 0)   
            {  
                perror("recvfrom");  
                exit(1);  
            }  
            fwrite (msgbuf, 1, nbytes, fp);
			printf ("write data %d bytes
", nbytes);
        }  
      
        return 0;  
    }